A teenager with measles was infectious when she visited Disneyland, Universal Studios and other tourist hotspots in Southern California earlier this month, public health officials said.

The teen was on a trip from New Zealand and flew into Los Angeles International Airport (LAX). She visited Disneyland Park and California Adventure among other attractions from Aug. 11-15. She also reportedly traveled to Universal Studios, Madame Tussauds and the Santa Monica Pier during the trip, the officials said.

Public health officials in Los Angeles and Orange counties said Friday they are attempting to find anyone who might have been exposed to the virus and has started showing symptoms.

Measles is one of the most contagious viruses in the world. Around 90 percent of unvaccinated people exposed to the virus will contract the disease within seven to 21 days. And those infected can transmit the virus to another person four days before and four days after its tell-tale rash appears, health officials said.

“Measles is spread by air and by direct contact even before you know have it,” Dr. Muntu Davis, Los Angeles County’s health officer, said in a statement. The potentially severe disease causes fever, rash, cough, and red, watery eyes.

According to the health agencies in Los Angeles and Orange counties, the teen visited Disneyland on Aug. 12 and Universal on Aug. 14. The average daily number of visitors at Disney was around 45,000 in 2015, according to the L.A. Times. Universal Studios had a record-high daily visitor count of 40,000 in 2017, the Times reported.

The infected teen was in Terminal 8 at LAX on the evening of Aug. 11 and at the Tom Bradley International Terminal on the evening of Aug. 15.

The CDC reports 1,203 individuals cases of measles in 30 states through Aug. 15, which was an increase of 21 cases from the previous week. This is the largest measles outbreak in the U.S. since 1992, and since measles was declared eliminated in 2000.

New Zealand is also struggling with a measles outbreak this year. Through mid-August, it had confirmed 639 cases of measles cases in 2019.

As officials continue to investigate, the California Department of Public Health said it wasn’t aware of measles cases stemming from exposure to the teen, the AP reported.

Measles, a virus that was eliminated in the United States some 20 years ago, has sprung back in recent years in many countries around the world, including the U.S. Outbreaks have been fueled in many countries, including the United States, by mistrust and misinformation campaigns about vaccine safety.

Dr. Nichole Quick, the Orange County health officer, urged everyone to seek an immunization if they had not already done so.

“We maintain rigorous sanitation standards to protect guests and cast, and earlier this year we strengthened our immunization program and educational resources for cast members, in addition to our ongoing efforts,” Pamela Hymel, the Chief Medical Officer of Disney Parks, said in a statement Friday.

Audrey Eig, a spokesperson for Universal Studios Hollywood, said studio officials “have been advised by the Department of Public Heath that there is minimal risk to any exposure at our destination.”

A 2015 measles outbreak linked to Disneyland led to 147 cases in multiple states as well as in Mexico and Canada. Many of those who were sickened either were unvaccinated or did not know their vaccine record, according to the CDC.